All the patients had the same terrible diagnosis: brain damage that marooned them in a “vegetative state” — alive but without any sense of awareness of themselves or the world around them.
But then an international team of scientists tried an ambitious experiment: By measuring electrical activity in the patients’ brains with a relatively simple technique, the researchers attempted to discern whether, in fact, they were actually conscious and able to communicate.
In most of the cases, there was nothing — no signs any sentience lingered. But then one man, then another, and, surprisingly, a third, repeatedly generated brain activity identical to that of healthy volunteers when they were asked to imagine two simple things: clenching a fist and wiggling their toes.
The findings, reported online Wednesday by the journal The Lancet, provide startling — and in some ways disturbing — new evidence confirming previous indications that a significant proportion of patients diagnosed as being vegetative may in fact be aware.
But, most importantly, the widely available, portable technology used in the research offers what could be the first practical way for doctors to identify and finally communicate with perhaps thousands of patients who may be languishing unnecessarily in isolation. Doctors could, for example, find out whether patients are in pain.
“You spend a week with one of these patients and at no point does it seem at all they know what you are saying when you are talking to them. Then you do this experiment and find it’s the exact opposite — they do know what’s going on,” said Damian Cruse, a post-doctoral neuroscientist at the University of Western Ontario in Canada who helped conduct the research. “That’s quite a profound feeling.”
The results and similar findings could also provide crucial insights into human consciousness — one of the most perplexing scientific puzzles — and lead to ways to better diagnose and possibly rehabilitate brain injury patients, the researchers said.
“Can you imagine spending years without being able to interact with anyone around you?” Cruse said. “We can ask them, ‘What it’s like to be in this condition? Do they know where they are? Do they know who is around them? What do they need?’ This will lead to very profound implications.”
Other experts, while praising the research, cautioned that much more work is needed to confirm the findings and refine the technology.
“Lay people will interpret these experimental results as a clinical test and they are not ready to be used that way,” said Nicholas Schiff, a neurologist at the Weill Cornell Medical College in New York.
As many as 20,000 Americans are in a vegetative state, meaning they are alive and awake but without any apparent sense of awareness, and 100,000 to 300,000 are in a related condition known as a minimally conscious state, in which they exhibit impaired or intermittent awareness. A growing body of evidence in recent years has indicated that a significant proportion might have more awareness than had been thought.
“It doesn’t mean all vegetative patients are aware. It is only some. But when you think of the number of patients that there are around the world in this situation, it is quite a lot,” said Adrian Owen, a neuroscientist at the University of Western Ontario who is the senior researcher involved in the work.
In 2006, Owen and his colleagues described a young woman thought to be in a vegetative state. Her brain responded identically to a normal brain when scanned with functional magnetic resonance imaging (fMRI) as researchers asked her to imagine playing tennis or exploring her home. The case electrified neuroscientists. But it remained unclear whether it was a fluke.
Then in February 2010, Owen’s team reported similar testing on 23 vegetative patients and 31 minimally conscious patients. Five repeatedly fired their brains in precisely the same way as normal volunteers as they underwent fMRIs while being asked to imagine hitting a tennis ball and wandering through their homes. One patient was able to answer yes or no to a series of questions by thinking about tennis for yes and touring his home for no.
But fMRIs are expensive and difficult to perform, and the equipment is not portable. “Many of these patients are vulnerable and it’s difficult to move them around. So it’s difficult to get access to this technology,” Owen said.
So, the researchers decided to try using a technique called electroencephalography, a time-tested way to precisely measure activity in different parts of the brain that is relatively easy and portable.
“We can take it to the patient, which effectively means that almost any patient in the community, in care homes and residential homes and hospitals, we can get to them,” Owen said. “We can establish how many of those patients are conscious.”
Between July 2010 and June 2011, the scientists tested 16 patients ages 14 to 63 at Addenbrooke’s Hospital in Britain and the University Hospital of Liege in Belgium who had been declared in a vegetative state. Some had been diagnosed eight years ago, others within the previous month. They had suffered head injuries from a car crash or some other accident, or had oxygen cut off to their brains, such as from a stroke.
The scientists asked the subjects to imagine making a fist with their right hand and then relaxing it and wiggling all the toes on both feet and then relaxing them. Twelve healthy volunteers were tested for comparison imagining the same things.
Three of the 16 — a surprisingly high 19 percent — generated normal EEG responses hundreds of times in response to the requests. The scientists could find nothing else unusual about them. All were male, ages 29, 35 and 45, who had been declared in a vegetative state three, nine and 23 months earlier.